The unwaning desire to decrease the cost and size of switching power converters has put a focus on the output filter. However, smaller inductance and capacitance puts a more stringent requirement on the DC/DC controller, which will need to provide faster transient response through a higher bandwidth control loop. Double-edge pulse-width modulation (PWM) has shown some benefits over single-edge PWM in achieving higher bandwidth DC/DC controllers. This is discussed, for example, in “Control-loop bandwidth limitations for multiphase interleaving buck converters,” by Yang Qiu, Kaiwei Yao, Yu Meng, Ming Xu, F. C. Lee and Mao Ye, Nineteenth Annual IEEE Applied Power Electronics Conference and Exposition, 2004. APEC '04, vol. 2, pp. 1322-1328. FIG. 1 shows an exemplary prior art double-edge PWM generated from an error signal (COMP) and a triangle wave oscillating signal (RAMP).
There is also a desire to provide a single PWM converter or module that can provide a wide range of input/output voltage and current ranges.